Connection between an integrated pressure management apparatus and a vapor collection canister

ABSTRACT

An integrated pressure management system manages pressure and detects leaks in a fuel system. The integrated pressure management system also performs a leak diagnostic for the headspace in a fuel tank, a canister that collects volatile fuel vapors from the headspace, a purge valve, and all associated hoses and connections.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the earlier filing date ofU.S. Provisional Application No. 60/166,404, filed Nov. 19, 1999, whichis incorporated by reference herein in its entirety.

Field of Invention

[0002] The present invention relates to an integrated pressuremanagement system that manages pressure and detects leaks in a fuelsystem. The present invention also relates to an integrated pressuremanagement system that performs a leak diagnostic for the headspace in afuel tank, a canister that collects volatile fuel vapors from theheadspace, a purge valve, and all associated hoses.

BACKGROUND OF INVENTION

[0003] In a conventional pressure management system for a vehicle, fuelvapor that escapes from a fuel tank is stored in a canister. If there isa leak in the fuel tank, canister or any other component of the vaporhandling system, some fuel vapor could exit through the leak to escapeinto the atmosphere instead of being stored in the canister. Thus, it isdesirable to detect leaks.

[0004] In such conventional pressure management systems, excess fuelvapor accumulates immediately after engine shutdown, thereby creating apositive pressure in the fuel vapor management system. Thus, it isdesirable to vent, or “blow-off,” through the canister, this excess fuelvapor and to facilitate vacuum generation in the fuel vapor managementsystem. Similarly, it is desirable to relieve positive pressure duringtank refueling by allowing air to exit the tank at high flow rates. Thisis commonly referred to as onboard refueling vapor recovery (ORVR).

SUMMARY OF THE INVENTION

[0005] According to the present invention, a sensor or switch signalsthat a predetermined pressure exists. In particular, the sensor/switchsignals that a predetermined vacuum exists. As it is used herein,“pressure” is measured relative to the ambient atmospheric pressure.Thus, positive pressure refers to pressure greater than the ambientatmospheric pressure and negative pressure, or “vacuum,” refers topressure less than the ambient atmospheric pressure.

[0006] The present invention is achieved by providing a volatile fuelvapor collection system. This system comprises an integrated pressuremanagement apparatus, a collection canister in fluid communication withthe integrated pressure management apparatus; and a connectionestablishing the fluid communication between the integrated pressuremanagement apparatus and the collection canister. The integratedpressure management apparatus includes a housing defining an interiorchamber, the housing including first and second ports communicating withthe interior chamber; a pressure operable device separating the chamberinto a first portion and a second portion, the first portioncommunicating with the first port, the second portion communicating withthe second port, the pressure operable device permitting fluidcommunication between the first and second ports in a firstconfiguration and preventing fluid communication between the first andsecond ports in a second configuration; and a signal chamber in fluidcommunication with the first portion of the interior chamber, thepressure operable device further separating the signal chamber from thesecond portion of the interior chamber.

[0007] The present invention is also achieved by a method of assemblinga volatile fuel vapor collection system. The method comprises providingcollection canister having a first one of a male and female members;providing an integrated pressure management apparatus having a secondone of the male and female members; and matingly engaging the male andfemale members with respect to one another. The integrated pressuremanagement apparatus has a pressure operable device separating aninterior chamber into a first portion and a second portion, the firstportion communicating with the collection canister, the second portioncommunicating with a vent, the pressure operable device permitting fluidcommunication between the collection chamber and the vent in a firstconfiguration and preventing fluid communication between the collectionchamber and the vent in a second configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated herein andconstitute part of this specification, illustrate the present invention,and, together with the general description given above and the detaileddescription given below, serve to explain features of the invention.Like reference numerals are used to identify similar features.

[0009]FIG. 1 is a schematic illustration showing the operation of anapparatus according to the present invention.

[0010]FIG. 2 is a cross-sectional view of a first embodiment of theapparatus according to the present invention

[0011]FIG. 3 is a cross-sectional view of a second embodiment of theapparatus according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0012] Referring to FIG. 1, a fuel system 10, e.g., for an engine (notshown), includes a fuel tank 12, a vacuum source 14 such as an intakemanifold of the engine, a purge valve 16, a charcoal canister 18, and anintegrated pressure management system (IPMA) 20.

[0013] The IPMA 20 performs a plurality of functions including signaling22 that a first predetermined pressure (vacuum) level exists, relievingpressure 24 at a value below the first predetermined pressure level,relieving pressure 26 above a second pressure level, and controllablyconnecting 28 the charcoal canister 18 to the ambient atmosphericpressure A.

[0014] In the course of cooling that is experienced by the fuel system10, e.g., after the engine is turned off, a vacuum is created in thetank 12 and charcoal canister 18. The existence of a vacuum at the firstpredetermined pressure level indicates that the integrity of the fuelsystem 10 is satisfactory. Thus, signaling 22 is used for indicating theintegrity of the fuel system 10, i.e., that there are no leaks.Subsequently relieving pressure 24 at a pressure level below the firstpredetermined pressure level protects the integrity of the fuel tank 12,i.e., prevents it from collapsing due to vacuum in the fuel system 10.Relieving pressure 24 also prevents “dirty” air from being drawn intothe tank 12.

[0015] Immediately after the engine is turned off, relieving pressure 26allows excess pressure due to fuel vaporization to blow off, therebyfacilitating the desired vacuum generation that occurs during cooling.During blow off, air within the fuel system 10 is released while fuelmolecules are retained. Similarly, in the course of refueling the fueltank 12, relieving pressure 26 allows air to exit the fuel tank 12 athigh flow.

[0016] While the engine is turned on, controllably connecting 28 thecanister 18 to the ambient air A allows confirmation of the purge flowand allows confirmation of the signaling 22 performance. While theengine is turned off, controllably connecting 28 allows a computer forthe engine to monitor the vacuum generated during cooling.

[0017]FIG. 2, shows a first embodiment of the IPMA 20 mounted on thecharcoal canister 18. The IPMA 20 includes a housing 30 that can bemounted to the body of the charcoal canister 18 by a “bayonet” styleattachment 32. A seal 34 is interposed between the charcoal canister 18and the IPMA 20. This attachment 32, in combination with a snap finger33, allows the IPMA 20 to be readily serviced in the field. Of course,different styles of attachments between the IPMA 20 and the body 18 canbe substituted for the illustrated bayonet attachment 32, e.g., athreaded attachment, an interlocking telescopic attachment, etc.Alternatively, the body 18 and the housing 30 can be integrally formedfrom a common homogenous material, can be permanently bonded together(e.g., using an adhesive), or the body 18 and the housing 30 can beinterconnected via an intermediate member such as a pipe or a flexiblehose.

[0018] The housing 30 can be an assembly of a main housing piece 30 aand housing piece covers 30 b and 30 c. Although two housing piececovers 30 b, 30 c have been illustrated, it is desirable to minimize thenumber of housing pieces to reduce the number of potential leak points,i.e., between housing pieces, which must be sealed. Minimizing thenumber of housing piece covers depends largely on the fluid flow pathconfiguration through the main housing piece 30 a and the manufacturingefficiency of incorporating the necessary components of the IPMA 20 viathe ports of the flow path. Additional features of the housing 30 andthe incorporation of components therein will be further described below.

[0019] Signaling 22 occurs when vacuum at the first predeterminedpressure level is present in the charcoal canister 18. A pressureoperable device 36 separates an interior chamber in the housing 30. Thepressure operable device 36, which includes a diaphragm 38 that isoperatively interconnected to a valve 40, separates the interior chamberof the housing 30 into an upper portion 42 and a lower portion 44. Theupper portion 42 is in fluid communication with the ambient atmosphericpressure through a first port 46. The lower portion 44 is in fluidcommunication with a second port 48 between housing 30 the charcoalcanister 18. The lower portion 44 is also in fluid communicating with aseparate portion 44 a via first and second signal passageways 50,52.Orienting the opening of the first signal passageway toward the charcoalcanister 18 yields unexpected advantages in providing fluidcommunication between the portions 44,44 a. Sealing between the housingpieces 30 a, 30 b for the second signal passageway 52 can be provided bya protrusion 38 a of the diaphragm 38 that is penetrated by the secondsignal passageway 52. A branch 52 a provides fluid communication, overthe seal bead of the diaphragm 38, with the separate portion 44 a. Arubber plug 50 a is installed after the housing portion 30 a is molded.The force created as a result of vacuum in the separate portion 44 acauses the diaphragm 38 to be displaced toward the housing part 30 b.This displacement is opposed by a resilient element 54, e.g., a leafspring. The bias of the resilient element 54 can be adjusted by acalibrating screw 56 such that a desired level of vacuum, e.g., one inchof water, will depress a switch 58 that can be mounted on a printedcircuit board 60. In turn, the printed circuit board is electricallyconnected via an intermediate lead frame 62 to an outlet terminal 64supported by the housing part 30 c. An O-ring 66 seals the housing part30 c with respect to the housing part 30 a. As vacuum is released, i.e.,the pressure in the portions 44,44 a rises, the resilient element 54pushes the diaphragm 38 away from the switch 58, whereby the switch 58resets.

[0020] Pressure relieving 24 occurs as vacuum in the portions 44,44 aincreases, i.e., the pressure decreases below the calibration level foractuating the switch 58. Vacuum in the charcoal canister 18 and thelower portion 44 will continually act on the valve 40 inasmuch as theupper portion 42 is always at or near the ambient atmospheric pressureA. At some value of vacuum below the first predetermined level, e.g.,six inches of water, this vacuum will overcome the opposing force of asecond resilient element 68 and displace the valve 40 away from a lipseal 70. This displacement will open the valve 40 from its closedconfiguration, thus allowing ambient air to be drawn through the upperportion 42 into the lower the portion 44. That is to say, in an openconfiguration of the valve 40, the first and second ports 46,48 are influid communication. In this way, vacuum in the fuel system 10 can beregulated.

[0021] Controllably connecting 28 to similarly displace the valve 40from its closed configuration to its open configuration can be providedby a solenoid 72. At rest, the second resilient element 68 displaces thevalve 40 to its closed configuration. A ferrous armature 74, which canbe fixed to the valve 40, can have a tapered tip that creates higherflux densities and therefore higher pull-in forces. A coil 76 surroundsa solid ferrous core 78 that is isolated from the charcoal canister 18by an O-ring 80. The flux path is completed by a ferrous strap 82 thatserves to focus the flux back towards the armature 74. When the coil 76is energized, the resultant flux pulls the valve 40 toward the core 78.The armature 74 can be prevented from touching the core 78 by a tube 84that sits inside the second resilient element 68, thereby preventingmagnetic lock-up. Since very little electrical power is required for thesolenoid 72 to maintain the valve 40 in its open configuration, thepower can be reduced to as little as 10% of the original power bypulse-width modulation. When electrical power is removed from the coil76, the second resilient element 68 pushes the armature 74 and the valve40 to the normally closed configuration of the valve 40.

[0022] Relieving pressure 26 is provided when there is a positivepressure in the lower portion 44, e.g., when the tank 12 is beingrefueled. Specifically, the valve 40 is displaced to its openconfiguration to provide a very low restriction path for escaping airfrom the tank 12. When the charcoal canister 18, and hence the lowerportions 44, experience positive pressure above ambient atmosphericpressure, the first and second signal passageways 50,52 communicate thispositive pressure to the separate portion 44 a. In turn, this positivepressure displaces the diaphragm 38 downward toward the valve 40. Adiaphragm pin 39 transfers the displacement of the diaphragm 38 to thevalve 40, thereby displacing the valve 40 to its open configuration withrespect to the lip seal 70. Thus, pressure in the charcoal canister 18due to refueling is allowed to escape through the lower portion 44, pastthe lip seal 70, through the upper portion 42, and through the secondport 46.

[0023] Relieving pressure 26 is also useful for regulating the pressurein fuel tank 12 during any situation in which the engine is turned off.By limiting the amount of positive pressure in the fuel tank 12, thecool-down vacuum effect will take place sooner.

[0024]FIG. 3 shows a second embodiment of the present invention that issubstantially similar to the first embodiment shown in FIG. 2, exceptthat the first and second signal passageways 50,52 have been eliminated,and the intermediate lead frame 62 penetrates a protrusion 38 b of thediaphragm 38, similar to the penetration of protrusion 38 a by thesecond signal passageway 52, as shown in FIG. 2. The signal from thelower portion 44 is communicated to the separate portion 44 a via a paththat extends through spaces between the solenoid 72 and the housing 30,through spaces between the intermediate lead frame 62 and the housing30, and through the penetration in the protrusion 38 b.

[0025] The present invention has many advantages, including:

[0026] providing relief for positive pressure above a firstpredetermined pressure value, and providing relief for vacuum below asecond predetermined pressure value.

[0027] vacuum monitoring with the present invention in its openconfiguration during natural cooling, e.g., after the engine is turnedoff, provides a leak detection diagnostic.

[0028] driving the present invention into its open configuration whilethe engine is on confirms purge flow and switch/sensor function.

[0029] vacuum relief provides fail-safe operation of the purge flowsystem in the event that the solenoid fails with the valve in a closedconfiguration.

[0030] integrally packaging the sensor/switch, the valve, and thesolenoid in a single unit reduces the number of electrical connectorsand improves system integrity since there are fewer leak points, i.e.,possible openings in the system.

[0031] While the invention has been disclosed with reference to certainpreferred embodiments, numerous modifications, alterations, and changesto the described embodiments are possible without departing from thesphere and scope of the invention, as defined in the appended claims andtheir equivalents thereof. Accordingly, it is intended that theinvention not be limited to the described embodiments, but that it havethe full scope defined by the language of the following claims.

What is claimed is:
 1. A volatile fuel vapor collection system,comprising: an integrated pressure management apparatus including: ahousing defining an interior chamber, the housing including first andsecond ports communicating with the interior chamber; a pressureoperable device separating the chamber into a first portion and a secondportion, the first portion communicating with the first port, the secondportion communicating with the second port, the pressure operable devicepermitting fluid communication between the first and second ports in afirst configuration and preventing fluid communication between the firstand second ports in a second configuration; and a signal chamber influid communication with the first portion of the interior chamber, thepressure operable device further separating the signal chamber from thesecond portion of the interior chamber; a collection canister in fluidcommunication with the first portion of the interior chamber; and aconnection establishing the fluid communication between the integratedpressure management apparatus and the collection canister.
 2. Thevolatile fuel vapor collection system according to claim 1, wherein thepressure operable device includes a diaphragm separating the signalchamber and the second portion of the interior chamber.
 3. The volatilefuel vapor collection system according to claim 1, wherein the pressureoperable device comprises: a poppet preventing fluid communicationbetween the first and second ports in the second configuration; a springbiasing the poppet toward the second configuration; and a diaphragmseparating the second portion of the interior chamber from a signalchamber in fluid communication with the first portion of the interiorchamber.
 4. The volatile fuel vapor collection system according to claim1, wherein a switch is disposed within the housing, the switch signalsdisplacement of the pressure operable device in response to negativepressure at a first pressure level in the first portion of the interiorchamber.
 5. The volatile fuel vapor collection system according to claim1, wherein the housing comprises a body that is integrally formed from ahomogeneous material and a minimum number of covers.
 6. The volatilefuel vapor collection system according to claim 1, wherein theconnection includes a female member matingly engaging a male member. 7.The volatile fuel vapor collection system according to claim 6, whereinthe connection is selected from a group consisting of a bayonet styleattachment, a threaded attachment, and an interlocking telescopicattachment.
 8. The volatile fuel vapor collection system according toclaim 6, wherein the connection further includes a lock preventingdisengaging the male and female members.
 9. The volatile fuel vaporcollection system according to claim 8, wherein the lock includes aresilient projection preventing relative rotation of the male and femalemembers.
 10. The volatile fuel vapor collection system according toclaim 1, wherein the connection includes integrally forming the housingand the collection canister from a homogeneous material.
 11. Thevolatile fuel vapor collection system according to claim 10, wherein theintegral connection minimizes a dimension of the housing and collectioncanister.
 12. The volatile fuel vapor collection system according toclaim 10, wherein the integral connection eliminates a leak pointbetween the housing and collection canister.
 13. The volatile fuel vaporcollection system according to claim 1, wherein the housing and thecollection canister are remotely located with respect to one another andthe connection includes an elongated conduit extending between thehousing and the collection canister.
 14. A method of assembling avolatile fuel vapor collection system, comprising: providing collectioncanister having a first one of a male and female members; providing anintegrated pressure management apparatus having a second one of the maleand female members, the integrated pressure management apparatus alsohaving a pressure operable device separating an interior chamber into afirst portion and a second portion, the first portion communicating withthe collection canister, the second portion communicating with a vent,the pressure operable device permitting fluid communication between thecollection chamber and the vent in a first configuration and preventingfluid communication between the collection chamber and the vent in asecond configuration; and matingly engaging the male and female memberswith respect to one another.